Approach locking for railways



April 21, 1936.

FlGl.

FIG.2.

s. N. WIGHT 2,038,503

APPROACH LOCKING FOR RAILWAYS Filed Aug. 6, 1925 4 Sheets-Sheet l Aprifi 21, 1936. s. N. WIGHT APPROACH LOCKING FOR RAILWAYS Filed Aug. 6, 1925 4 Sheets-Sheet -2 mON 7 April 21, 1936. s. N. WIGHT APPROACH LOCKING FOR RAILWAYS Filed Aug. 6, 1925 4 Sheets-Sheet 3 .LVGE

April 21, 1936. 5 w|GHT 2,038,503

APPROACH LOOKING FOR RAILWAYS Filed Aug. 6, 1925 4 Sheets-Sheet 4 o i2] $1 E] IE I r- I 0 HF V Q E 9 M/ m L: I:

l atentecl Apr. 21 1936 UNITED srrss APPROACH LOGKING FOR RAILWAYS Sedgwick N. Wight, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application August 6, 1925, Serial No; 48,554

40 Claims.

This invention relates to a switch and signal control system, and more particularly to a system of this kind applied to a passing siding of a single track railroad.

One of the principal objects, purposes and characteristic features of the present invention resides in the provision of an arrangement of circuits and devices for operating the switches and. controlling signals for governing the movement of trains into and out of the siding and main track of a passing siding of single track railroads semi-automatically and in a manner to assure safety; in permitting the power-operated switch to be operated by power only if all the signals adjacent to such switch machine are at stop, so as to properly inform approaching trains of the contemplated operation of the switch machine; in providing locking means for preventing operation of such power-operated switch by the towermen even if such signals are at stop, and effective if there is a train within a prescribed distance of said switch on the main track, and in providing releasing means which can be operated only if the towerman and a train man of a locked up train properly cooperate. Other objects of the invention consist in the provision of'indicating means in thetower to inform the operator as to the position of the power-operated switch, and the occupancy of certain track portions whereby the direction of movement of a passing train may be determined.

Other objects and features of the present invention will in part be described hereinafter and in, part be obvious from the drawings.

In describing the invention in detail reference will be made to the accompanying drawings in which:--

Fig. 1 is a lay-out of a stretch of single track railroad equipped with an absolute-permissive block signaling system, in which the signals associated with the siding at the left hand thereof are such, and are positioned in a manner, as to be capable in connection with the rest of the apparatus of carrying out the present invention;

Fig. 2 shows conventionally the power-operated switch machine, the tower with the desk circuit controller shown conventionally, and certain of the other apparatus used in the novel system; and

Figs. 3, 4 and 5 illustrate respectively, the signaling circuits, the switch machine control circuits, and the approach locking and releasing circuit of a system embodying the present invention.

' System A. P. B.Referring to Fig. 1 there has been shown a stretch of single track 0 equipped with a block signaling system of the well-known absolute-permissive type, of which the east end of the siding F shown is equipped with switch and 7 signal control mechanism embodying the present invention and in which the left or west end of the siding G is not so equipped. Of these signals the signals 2, 4, 6 and 8 govern traffic moving from west to east, that is, from left to right; whereas the signals 1, 5, 3 and l govern traffic moving from east to west. The signals 2 and l are the usual starting signals used in absolutepermissive block signaling, conveniently called A. P. B. signaling, except that the signal 2 is set back a distance so that it does not govern the movement of trains off of the siding F, the added dwarf starting signal D being used for this purpose. The dwarf signal D is a stop-and-stay signal the same as is the signal 2 as indicated by the square ended blades employed in these sig- I nals, and according to the rules laid down by the railroads signals of this kind are not to be passed, unless they indicate proceed. Also, the signal I governing traflic into the siding F is a stop-and stay signal as indicated by its square ended blade contrary to that of the signal 8 governing traffic into the siding G which latter signal corresponds to and is interpreted as the usual automatic signal. The signal I governs traffic moving from right to left into the main track of the passing siding F, and the diverging route signal DR governs the movement of trafiic into the siding, this diverging route signal DR also being a stop-andstay signal. The reason that all four signals at the east end of passing siding F are all stop-andstay signals, is to safeguard the apparatus against a train moving into the siding while the switchmachine SM operating the switch'lil (see Fig. 2) is in operation. a As heretofore mentioned, the signals of the stretch of single track 0 are of the absolute-permissive type and assume the position shown under normal clear traffic conditions. If a train enters the stretch of single track 0 from the left end,

the signals l, 3, 5 and 1 immediately assume the danger position, thereby blocking all movements of traflic from east to west; as this train passes the signal l the signal 3 adjacent thereto is permitted to assume the caution position, for reasons hereinafter explained, as the train passes the signal 6 the signal 5 adjacent thereto is permitted to clear; and as the train moves entirely by the signal 8 the signal i is permitted to assume its clear position. On the other hand, as the train just mentioned passes from west to east through this stretch of single track 0, the signals governing traffic from west to east in the rear of such train assume the danger position so long as this train occupies the space between it and the next signal ahead, assumes the caution position so long as the train occupies the track between the first and the second signal in advance thereof and assumes the clear position when the train passes beyond the second signal in advance thereof. In other words, the signals governing direction of trafiic in which a train is moving indicate traffic conditions in the same manner as do signals in the usual three-position double track system; whereas the signals governing traflie in the opposite direction to that in which the train is moving all assume the danger position when such train enters the stretch of single track and clear up as soon as the train passes such signal, so that all signals ahead of the train block the movement of traflic toward such train. For further information in regard to the control for the signals of an absolute-permissive block system of this kind, reference may be had to my prior Patent No. 1,294,736, dated Feb. 18, 1919.

Referring to Fig. 2 the fouling track circuit at the east end of siding F includes a track battery II and a track relay l 2, and the first two sections of track which are separated by insulated joints l3 contain track batteries l4 and I5 and track relays l6 and ll, respectively.

Supplemental apparatus The switch machine SM forming part of the present invention is one of the usual construction and is more specifically described in the patent to Howe No. 1,468,903, dated September 4, 1923. In addition to the switch machine SM a switch box 29, having movable contacts 2| and 22 movable in accordance with the movement of the switch it, is also employed. In the tower e is provided, among other things, a desk circuit controller DC. This desk circuit controller DC includes an operating handle (not shown) connected to the operating shaft 39 which is normally locked by the locking sector 3! against movement past its intermediate position by the pawl 32 operated by the locking magnet 33, suitable circuit closers, such as contact 34, being provided which are operated in accordance with movement of the shaft 39. In practice, this desk circuit controller is so designed that preliminary movement of the handle sufiicient to allow the relay NR or RR, as the case may be, to be deenergized before the handle reaches the position in which it is locked by the locking sector 3|, is provided. This provision is made so that all of the signals may be put to stop, and in turn the relay Z may become energized to permit energization of the locking magnet 33 through a circuit and for reasons more clearly described hereinafter. This desk circuit controller also includes suitable indicators; such as indicators N and R, which indicate whether the switch machine SM is in the normal or the reverse position respectively; the fouling track circuit indicator T, which indicates whether the fouling track circuit including track relay I2 is occupied or unoccupied; and the approach indicator A, which indicates whether or not the track within a cer tain distance east of the siding F is occupied or unoccupied. For further information in regard to the construction of this desk circuit controller DC, reference may be had to the patent of R. C. Leake, No. 1,589,319 dated January 15, 1926; in which this controller is described in detail.

Signal control In the usual A. P. B. signaling system the entering signal to one end of a passing siding is governed by the starting signal at the other end of the siding in a manner so as to cause the entering signal to indicate caution when the starting signal indicates stop. Each of the various signals shown, except the diverging route signal DR is controlled by a home or line relay, which relays have been designated H containing an exponent corresponding to that of the reference number of the signal. Considering the home relay H for the signal 5, this relay is controlled by a pole changer switch controlled by the signal T and assumes its normal position, in which it is shown, when the signal 1 is in either the clear or caution position, and assumes the reversed dotted position when the signal '5 the danger position. The energizing circuit for this home relay H may be traced as follows:- beginning at the battery ii through the pole changer switch at of the signal 7, wire 42, front contact 43 of the first track circuit beyond the west end of siding F, wire it, front contact 45 of the track relay of the main track of passing siding F, wire 46, front contact *3? of the fouling track circuit relay 52, wire 48, front contact 59 of the normal relay NR, wire 39, contact 56 of the switch machine SM, wire 5!, contact 22 of box 29, wire 52, winding of the home relay H to common return wire C connected to the other side of battery 4! through the pole changer switch it. With the polar neutral home relay H energized to its normal position as shown, the signal I assumes the clear position through the front contact 53, polar contact 56, and clearing wire 54; and when the relay H assumes the reverse position the signal I assumes the caution position through the medium of caution wire 55.

In a similar way, the home relays H and HI) are controlled by the pole changer switch 58 of the signal 4. Under normal conditions of the apparatus shown, the relay H is energized through the following circuit:-beginning at the battery 52, pole changer switch contact 58, the

. contact 59 of the signal 4 closed when the signal is in the clear position, the front contact iii of the home relay H .and the front contact 52 of the stick relay S all three in multiple, the wire 63, back contact 64 of the stick relay S wire 65, front contact 65 of the track relay ll, wire 61, front contact 68 of the track relay i5, wires 59 and 19, front contact l! of the normal relay NR, wire 72, contact 2i of the switch box 29, wire '13, winding of the home relay H wires i5 and ?5, front contact it of the fouling track circuit relay 1? to common return wire C connected to the other terminal of battery 59 to the pole changer blade 17. The signal 2 is controlled by the home relay H in the same manner as signal I is controlled by the home relay H so that the specific control circuits through the contacts of this relay need not be considered.

is in Let us for the purpose of studying circuits assume that the switch machine SM is operated to the reverse position under which condition the switch box contacts assume the dotted position, the reverse relay RR assumes the energized position and the normal relay NR assumes the de-energized position. Under this condition of the apparatus the home relay HD is energized through the following circuit:starting at the battery 59 through the various contacts and circuit portions up to and including the wire I9, heretofore traced in connection with the energizing circuit for relay H and from thence through wire 88, front contact 8| of the reverse relay RR, wire 82, contact 22 in its dotted position, wire 83, winding of the relay HD wires 84 and I5, front contact I6 of the track relay I2, common return wire C connected to the other side of battery 59 through pole changer blade 11. Also, under this assumed position of the apparatus the diverging route signal DR is energized through the following circuitz-beginning at the terminal B of a suitable source of energy, wire 86, front contact 81 of the reverse relay RR, wire 88, contact 89 of the switch machine SM, wire 98, contact 2| when in its dotted position, wire 9|, signal control mechanism of the signal DR. to a common return wire C connected to the other side of said source of energy.

Let us now assume that the apparatus is again in its normal condition as shown. By studying the circuits for the relays H H and HD and also the control circuit for the signal DB and bearing in mind that the relays NR and RR cannot bothbe energized at the same time, as readily appears from Fig. 4 of the drawings without tracing their energizing circuits, that either the signals I and 2 may be cleared which signals indicate trafic conditions for the main track or the signals D and DR may be cleared which signals indicate traflic conditions leading into or out of the siding. Also, it readily appears, bearing especially in mind that the four control circuits for the four signals each contain a contact in the switch box 28 and each include a contact of either the normal relay NR or the reverse relay RR, that if the reverse relay is energized with the switch normal or the normal relay is energized with the switch reversed that all of these four signals assume the stop position. This is important in connection with certain locking features affording approach looking more particularly described hereinafter and shown in Fig. 5 cf the drawings.

Before we leave the signal control circuits which are more specifically shown in Fig. 3 of the drawings let us consider the energizing circuit for the home relay H governing the signal 3, this in order to illustrate how the signal 3 will assume the caution position if either the signal I assumes the stop position or the signal 'I and D" both assume the stop position because there is a train moving from west toeast in the stretch of single track west of the siding F, and relays H and Hi) are both ole-energized. In order to obtain this control for the signal 3, a pole changer relay PC is required, which relay is energized if the following circuit is closed:beginning at the terminal B of a suitable source of energy, contact 94 operated by the signal I and closed when the signal assumes the clear, the caution or any intermediate position, wire 95, winding of the pole changer relay PC, wire 96 and the contacts 9-1, 98 and 99, connected in multiple, and controlled by the home relay H home relay HD' and stick relay S respectively, wire I08 to common return wire C connected to the other side of said source of energy. With the pole changer relay PC energized and certain other contacts closed the polar-neutral home relay H is energized to a position to clear the signal 3 through thefollowing circuit-beginning at the battery I92, pole changer contact I93 of the pole changer relay PC, wire I88, front contact I06 of the track relay l6, front contact I91 of the track relay Ill, Wire I98, back contact I09 of the stick relay S wire III! winding of the home relay H to the common return wire C connected to the other side of battery I92 through the pole changer contact Ill-l. From this circuit it appears, that if the pole changer relay PC is de-energized either because the signal I is at the stop position or because the home relays H and HD' are de-energized for any reason and when the stick relay S is not energized, the signal 3 assumes the caution position by reason of reversal of the polarity of the energizing current for the relay H With this understanding of the control circuits for the various signals let us consider the operation of the switch machine, the control circuits of which are shown in Fig. 4.

Switch machine control As clearly pointed out in connection with the control for the signals at the east entrance to the siding F all four of these signals will assume the stop position if the control relays NR and RR for the controlling switch machine SM are out of step, so to speak, with the switch box contacts 2I and 22 (see Fig. 3).

With these interlocking features in mind, let us assume that the operator in tower 9 desires to operate the switch I 9 to the reverse position and let us further assume that the locking mag: net 33 is energized so that the operator is free to move the handle of the desk circuit controller DC. As the operator moves the desk circuit controller to the right hand dotted position, he deenergizes the normal relay NR, which is normally energized through the following circuit:beginning at the battery H2, or other suitable source of energy, contact 34 of the desk circuit controller DC, wire H3, back contact II4 of the reverse relay RR, wire H5 through the winding of the relay NR to the common return wire C connected to the other side of this battery II2. With this contact 34 moved to the right hand dotted position and the relay NR de-energized the following circuit for the relay RR is completed: beginmng at the battery H2, contact 34 of the desk circuit controller in its dotted position, wire IIE backcontact II'I of the normal relay NR, wire I I8, winding of the reverse relay RR to the common return wire 0. This de-energization of the relay NR and energization of the relay RR brings these relays out of step with the switch box contacts and causes the four signals toassume the stop position.

With the four signals I, DB 2 and D in the stop position, with the front contact I 3| of the track relay I2 closed and with the crank 93 used for operating the switch machine SM manually, in its housed position in the telephone cabinet I20, the relay Z is energized through the following circuit:-beginning at the terminal B of a suitable source of energy, Wire I 2I crank signal DB and closed when this signal is in a stop position, wire I24, contact I25 controlled by the signal I and closed when this signal is in its stop position, wire I26, contact I21 controlled by the dwarf signal D and closed when this signal is in its stop position, wire I28, contact I29 of the signal 2 and closed when this signal is in its stop position, wire I30, front contact I3I of the track relay I2, wire I32, winding of the relay Z, the common return wire C connected to the other side of said source of energy. With the relays Z and RR energized and the relay NR de-energized the following circuit is closed, which operates the switch machine and in turn the switch It to the reverse position:beginning at the terminal B of a suitable source of energy, wire I36, front contact I31 of the relay Z, wire I33, field winding I39 of the switch machine motor, wire I43, contact M! of the switch machine SM, wire I42, back contact I43 of the normal relay NR, wires I44 and I45, armature I46 of the switch machine motor, wire I41, contact I48 of the repeater relay RR in its upper position to the common return wire C connected to the other side of said source of energy. With this circuit closed the switch machine operates the switch III to the reversed position and when it has almost reached such position the contacts MI and I49 shift very quickly and thereby break the energizing circuit for the motor, and by suitable means not shown snub the motor of the switch machine as more clearly described in the patent to Howe heretofore referred to. With this circuit broken the switch machine motor will stop and by reason of the shifting of contacts on the switch machine, assuming favorable traffic conditions ahead to exist, one of the four signals will at least clear up and in so doing will de-energize the relay Z, which will short-circuit the motor armature I45 through the following circuit:-beginning at the armature I46, wires I41 and I53, back contact I54 of the relay Z, wires I55 and I45, back to the armature I46. This shunting. circuit for the armature E43 is employed to guard against operation of the motor by unauthorized currents, or the like. In this connection it may be pointed out that the contacts 50, 89, E59, I85, IBI and I62 of the switch ma chine are operated in accordance with the gradual movement of the switch It from one position to the other, whereas the contacts. MI and I49 of this switch machine are operated through suitable lost motion mechanism and, are quickly shifted near the end of the stroke of" the switch machine.

In the same manner as just described the switch machine SM may be shifted from, the reverse to the normal position when the relays Z and NR. are energized and the relay RR is deenergized, through the following circuitz-beginning at the terminal B, wire I36, front contact I31 of the relay Z, wire I38, field winding I39 of the switch machine motor, wire I65, contact I49 of the switch machine, wire I63, contact I48 of the relay RR in its lower position, wire I41, armature I46 of the switch machinemotor, wires I45 and I44, contact I43 of the relay NR in its upper position, wire I61to the common return wire C connected to the other side of said source of energy. It should be noted that the circuit just traced causes current to flow from the terminal B of the battery through the field winding I39 in the same way as it does in the circuit for operating the switch tothe reverse position 1 but that the current flowing through the armature I46, has been reversed so that the torque in the motor has been reversed and the switch machine operates the switch in the opposite direction back to its normal position.

Approach locking From the various control circuits just considered, it readily appears that the crank for the switch machine must be in its housed location in the telephone cabinet, all of the signals governing the east end of the siding F must be in their stop positions, the fouling track circuit at the entrance to the siding must not be occupied and the operator in the tower must be free to operate the desk circuit controller before this switch machine can be operated. There is, however, a lock magnet 33 associated with the desk circuit controller DC, which look prevents the man in the tower from operating this circuit controller under certain conditions of traffic, and the control circuit for this lock magnet 33 conventionally called an approach locking circuit will now be considered. The approach lock including the magnet 33 of the desk circuit controller DC has its operating conditions based on the premise, that the desk circuit controller shall not be moved by the neutral position if there is a train approaching the switch II) from either direction on the main track for a distance which assures that an approaching train will be stopped before it reaches the switch I0, if either of the fouling track circuits usually provided at the ends of a passing siding are occupied and if the track circuit of themain track between such fouling track circuits is occupied.

In order to get this control in a comparatively simple manner a lock relay K has been provided (see Fig. 5), which relay is one of the stick type and which may be picked up if the home relay H is energized and either the track relay I8 is energized or the signal 3 is in the caution or danger position through the following pick-up circuit:beginning at the terminal B of a suitable source of energy, wire I16, front contact I1I of the home relay H wires I12 and I 13, winding of the relay K, wire E14, and then through either of the following two branches (1) wire I and contact I13 of the track relay I8 to thecommon return wire C, or (2) wire I11 and contact I18 connected to the common return wire C if the signal 3 is in either the caution, danger or any intermediate position. Also, with this look relay K once energized it remains energized through the following stick circuit even though the home relay H assumes the de-energized position:--beginning at the battery terminal B of said, source of energy, wire I88, stick contact I8I of the lock relay K, wires I 82 and I13, winding of the relay K, wire I14 and either of the branches heretofore mentioned in connection with the pick up circuit for this relay.

In studying these pick-up and stick circuits for the look relay K just considered, it readily appears that with this stick relay once energized, as it is normally, a train moving from left to right into the stretch of single track causes the home relay H to be ole-energized as soon as the direction of traffic has been selected by the train entering this stretch of single track, as is true of all absolute-permissive block signaling systems and as more clearly described in my prior patent heretofore referred to; and this dropping of the relay H and movement of this signal 3 to the danger position causes this stick relay K to remain energized in spite of dropping of the home relay H and dropping of the track relay I8 as the train in question moves from left to right through the stretch of single track. In other words, a train moving from left to right through the stretch of single track 0, will not de-energize this relay K if signal 3 is at stop. In this connection it should be remembered that thesignal 3 does not clear or even assume the caution position immediately in the rear of an east bound train as is true in absolute-permissive block signaling systems generally, this because the energizing circuit for the relay H includes a back contact of the stick relay S which stick relay is picked up upon passage of an east bound train and remains up so long as the line relay H is held retracted by such east bound train. 7

Let us now consider a train moving from right to left through this stretch of single track 0, trafiic conditions otherwise being clear, under which conditions the relay H is energized and the signal, 3 assumes the clear position. As'this train in question, moving from east to west, enters the track circuit containing track relay It the lock relay K assumes its de-energized position, because both branches of the stick circuit connected to the common return wire C are open and with this relay K once de-energized, re-closure of the contacts I76 will not cause this relay to again pick up when the rear end of the west bound train just mentioned passes off of the track circuit containing this track relay I8, the contact I18 will not close until the train has passed the signal 3 and when it does close it does not pick up relay K, so that the relay K remains de-energizecl. The relay K picks up, however, when the train has passed the signal I because home relay H is then again energized and with the track relay H in its energized condition the circuit for relay K is completed. The net result is, that a train moving from west to east through the stretch of track including relays I6, I1 and I8 causes the relay K to remain energized and a train moving from right to left through this same section. and with signal 3 in its clear position causes the relay K to be tie-energized and remain so during the time the train occupies this stretch of track.

Let us now consider how the relay K is again energized after a train moving from east to West passes beyond the signal I in its west bound direction. Referring to Fig. 3, it will be noted that .the relay H3 is energized either positively or negatively if the track relays I6 and H are energized and the stick relay S is de-energized so that the signal 3 moves to the caution position as soon as the rear end of the train has passed signal I and in so doing completes thepickup circuit of relay K heretofore traced which includes the front contact I'II of the relay H and the contact I18 of the signal 3.

At the second signal location west of the passing siding F is preferably located a similar locking relay K which is controlled by the signal contact of the signal 53 and its associated relays in the same manner as the relay K is controlled'by the apparatus adjacent to signal 3, so that the specific circuit arrangement for energizing relay K need not be discussed specifically. In addition to the control effected by the relays K and K upon the locking of the desk circuit controller the occupancy of the main track of the passing siding F and the fouling track circuits at the two ends of this siding must be considered in connection with the approach locking circuit.

This circuit may be traced as follows:-beginning at-the terminal B of a suitable source of energy, front contact I of the relay K wire I88, front contact I81 of the fouling track circuit relay 9I8, wire I88, front contact I89 of the track relay of the main track of the passing siding F, wire I99, front contact I9! of the lock relay K, wires I92 and I93, front contact I94 of the relay Z, wire I95, front contact I93 of the fouling track circuit relay I2, wire I9'I, winding of the lock magnet 33, wire I98 to common return wire C connected to the other side of said source of energy. It is of course impracticable to lock the switch machine SM entirely against operation if there is a train approaching the passing siding F or is standing on the main track of such siding, and the present invention contemplates that if a trainman of such locked up train cooperates with the towerman, and operates the push button 290 located adjacentthe telephone 20I in response to instructions given by the towerman to him, he completes an auxiliary circuit for the lock magnet 33, which circuit can readily be traced in Fig. 5 of the drawings. 7

Operation of the system ing without first stopping and a switchman throwingthe switch by hand, as is the usual prac-- tice. So long as the train is to the right of the track section containing relay I8 the relay K is energized and the locking magnet is likewise energized so that the desk circuit controller may be freely operated. As the desk circuit controller is operated to the right hand dotted or reverse position therelay RR is energized and the relay NR is de-energized; this causes the four signals at the east entrance of siding F to assume the stop position, thereby effecting energization of the relay Z, whereupon current is applied to the motor of switch machine SM and causes the switch machine to operate through a cycle and place the switch II] in the reverse position. Since west bound direction of trafiic has been set up in the single track section 0 the home relay H is de-energized and the signal 4 assumes its stop position, whereby both the relay H and the relay I-ID assume their de-energized position so that neither the signal 2 nor the signal D may be cleared; also, since the switch box contacts are in their reverse position, the switch machine SM is in its reverse position and the reverse relay RR is energized, the energizing circuit for the diverging route signal DR is completed so that this signal assumes the 45 degree or proceed position, this being a zero to 45 degree signal. As soon as the train in question entered the stretch of single track 0, for reasons heretofore given, this selection of the direction of traffic caused the home relay H to assume the de-energized position which in turn caused the signal 4 and then the signal 2 to assume the stop position the operator in tower 9 was advised by the approach indicator P A of the fact that west bound traflic had been selected for this stretch of single track. The

energizing circuit for this approach indicator A may be traced as follows:.beginning at the battery 59, polechanger switch blade 58, the contacts 60, SI and 62 controlled by signal 4, relay H and relay S all in multiple, wire 53, back contact 6% of stick relay S wire 65, front contact 66 of relay ll, wire 6?, front contact 68 of relay l6, wires es and 295, winding of the indicator A, wire 255 to common return wire C connected to the other side of battery 59 through pole changer switch blade ll. This circuit remains open until the train has passed entirely out of the stretch of single track 0, because the stick relay S picks up before the home relay H is energized so that the circuit is broken at contact 64 of stick relay S before it is completed at contact (ii of home relay H As soon as this train reaches the fouling track circuit containing track relay I2, the track circuit indicator T indicates the presence of a train on this fouling track circuit by reason of opening of front contact 281 of the track relay l2, readily traced in the drawings (see Fig. 4:). After the train has passed entirely onto the siding F in response to the indication of diverging route signal DR the lock relay K which, of course, was de-energized during the approach of this train, again assumes its energized position, as also does the fouling track circuit relay l2, so that the towerman is free to again restore the switch Ill to its normal main track position.

et us now assume that the operator in the tower by reason of negligence, lack of information, or the like, did not operate the switch machine to the reverse position before a west bound train moving in the stretch of single track 0 reached the track circuit containing track relay i3, and for this reason due to de-energization of the lock relay K is unable to operate the switch machine SM. Under this condition, proceeding on the assumption that the train crew has a train order which tells them to take the siding, the rain will be stopped at signal I and the engineer or train conductor will immediately get into communication with the operator through telephone 2% l and the operator will instruct the engineer to depress the push button 2% and while this push button is depressed and the lock magnet 33 is ener ized, the relay Z being energized because the operator has made a preliminary movement, permitted by the lost motion afforded by pawl 32, of the lever 34 sufficient to deenergize the relay NR and place the signal I at stop, the operator will move the circuit controller to the dotted position and in so doing reverse the switch Ii! by operation of the switch machine SM.

It is thus seen that the switch machine SM is protected against malicious or accidental operation in the face of an approaching train, and that means is provided whereby if the train crew and the operator properly cooperate the switch machine may be operated in spite of the approach locking mechanism employed, for protecting the switch machine against such malicious or accidental operation, by the provision of the release locking means consisting of a push button 2&6 and associated mechanism.

Although in the particular arrangement illustrated the switch machine is locked against operation if a train approaches from either direction within limited distances, the present invention is not limited to locking means extending in both directions, but may be employed where a single track system enters an interlocking plant or a double track system, in which event the relay K and the front contacts l8! and I89 will be omitted.

In my other application, Ser. No. 48,553 filed on the same day as this application, there is disclosed an organization for providing approach looking for a power operated switch machine; and the broad subject matter common to these two applications is claimed in said other application, Ser. No. 48,553.

Having thus shown and described one rather specific circuit arrangement whereby the operation of signals and switches at the ends of passing sidings of a single track railroad may be operated electrically by a block operator, and having shown rather specifically how the signals are to be located and what the interpretation of the Various indicating positions of the signals are; it is desired to be understood that this has been done for the purpose of illustrating an application of the invention rather than the specific means preferably employed in practicing the invention, and that various changes, modifications and additions may be made to adapt the invention to any one of the various problems encountered in practice without departing from the scope of the invention or the idea of means underlying the same.

What is desired to be secured by Letters Patent 1. A single track railway system having a siding, a plurality of signals at the entrance to said siding governing the entrance and departure of trains to and from said siding and the main track adjacent said siding, a power-operatcd switch machine for operating the switch leading to said siding, a relay at said siding for controlling said switch machine, control means for operating said relay from a distant point, and means for controlling said signals jointly by said switch machine and said relay, said control means under certain conditions for effective operation thereof requiring the cooperation of perso at said distant point and at said siding.

2. A single track railway system having a siding, a plurality of signals at the entrance to said siding governing the entrance and departure of trains to and from said siding and the main track adjacent said siding, a power-operated switch machine for operating a switch leading to said siding, a relay at said siding for controlling said switch machine, control means at times requiring the cooperation of two persons for operating said relay from a distant point, said switch machine being responsive only to a change in the condition of said relay if there are no trains within certain limits of said switch and all of said signals assume the stop position, and means for permitting said signals to assume a more favorable trafiic indicating condition including contacts operated by said relay and by said switch machine.

3. A single track railway system having a siding, a plurality of signals at the entrance to said siding governing the entrance and departure of trains to and from said siding and the main track adjacent said siding, a power-operated switch machine for operating a switch leading to said siding, a relay at said siding for controlling said switch machine, control means for operating said relay from a distant point at times requiring the cooperation of two persons one located at said distant point and the other located at said siding, means for controlling certain of said signals in accordance with the operated position of said p switch machine and the condition of said relay, and means for advising an operator at such distant point when said switch machine has started and when it has completed its operating stroke.

4. Semi-automatic switch and signal control ing traffic leading off of the main track into the stretch of single track, another starting stop-andstay signal located at the siding, a main track signal and a diverging, route signal located at the end of the stretch of single track and governing the movement of traffic into said main track and said siding respectively, means manually controllable for permitting either the two main track signals or said another starting signal and said diverging route signal to be cleared at one time, said manually controllable means at times for effective operation to control said signals requiring the cooperation of two persons.

5. Semi-automatic switch and signal control apparatus for governing trafiic from a stretch of single track into a siding or main track adjacent thereto and governing trafiic out of such siding or main track comprising, a main starting stopand-stay signal located on the main track back of the switch leading to said siding and governing traflic leading off of the main track into the stretch of single track, another starting stop-andstay signal located at the siding, a main track signal and a diverging route signal located at the end of the stretch of single track and governing the movement of trafiic into said main track and said siding respectively, and interlocked means manually controlled from a distant point whereby only one of the two starting signals may be cleared at one time, said manually controllable means'at times requiring the cooperation of two persons for efiective operation thereof one located at said distant point and the other located at said siding.

6. Semi-automatic switch and signal control apparatus for governing traific from a stretch of single track into a siding or main track adjacent thereto and governing traflic out of such siding or main track comprising, a main starting stop-and-stay signal located on the main track back of the switch leading to said siding and governing trafiic leading off of the main track into the stretch of single track, another starting stopand-stay signal located at the siding, a main track signal and a diverging route signal located at the end of the stretch of single track and governing the movement of traffic into said main track and said siding respectively, manually controllable interlocked means whereby only one of the two starting signals may be cleared at one time, and indicating means for indicating which one of the two starting signals is permitted to clear.

7. Semi-automatic switch and signal control apparatus for governing traflic from a stretch of single track into a siding or main track adjacent thereto and governing traflic out of such siding or main track comprising, a main starting stop-and-stay signal located on the main track back of the switch leading to said siding and governing traflic leading off of the main track into the stretch of single track, another starting stopand-stay signal for governing movement of traffic off of said siding, a main stop-and-stay signal and a diverging route stop-and-stay signal located at the end of the stretch of single track and governing the movement of trafiic into the main track and siding respectively, a switch machine for operating the switch of said siding, means for controlling said switch machine from a distant tower, means for controlling said signals in accordance with traflic conditions and the operated position of said switch machine, means for locking said switch machine against operation if there is an approaching train within a limited distance of said switch, and means effective if a trainman of a locked up train and an operator at such tower properly cooperate to render such locking means inefiective.

8. Semi-automatic switch and signal control apparatus for governing traffic from a stretch of single track into a siding or main track adjacent thereto and governing traffic out of such siding or main track comprising, a main starting stopand-stay signal located on the main track back of the switch leading to said siding and governing traffic leading off of the main track into the stretch of single track, another starting stopand-stay signal and located to govern the movement of traffic off of the siding, a main track stop-and-stay signal and a diverging route stopand-stay signal located at the end of the stretch of single track and governing the movement of trafiic into the main track and siding respectively, a switch machine for operating the switch of said sPding, means for controlling said switch machine and said signals from a distant tower, the control of the signals being dependent on the operated position of the switch machine, and means for locking said switch machine against operation comprising a normally energized relay which remains energized even though there is a train within a limited distance of said switch machine moving away from said switch but which assumes its de-energized condition if such train is moving toward said switch.

9. Semi-automatic switch and signal control, apparatus for governing traffic from a stretch of single track into a siding or main track adjacent thereto and governing trafilc out of such siding or main track comprising, a main starting stopand-stay signal located on'the main track back of the switch leading to said siding and governing trafiic leading off of the main track into the stretch of single track, another starting stop-- and-stay signal located at the siding, a main track stop-and-stay signal and a diverging route stop-and-stay signal located at the end of the stretch of single track and governing the movement of traflic into the main track and siding respectively, a switch machine for operating the switch of said siding, means for controlling said switch machineand said signal from a distant tower, the control for the signals being dependent on the operated position of said switch machine, and means for locking said switch machine against operation comprising, a stick relay having a stick circuit which is closed it a signal at least braking distance away from said switch governing traiiic toward said switch is either in the caution or stop condition or the first track circuit beyond said signal is not occupied.

' 10. Semi-automatic switch and signal control apparatus for governing traffic from a stretch of single track into a siding or main track adjacent thereto and governing traffic out of such siding or main track comprising, a main starting stop-and-stay signal located on the main track back of the switch leading to said siding and governing traffic leading to said siding and governing traffic leading off of the main track into the stretch of single track, another starting stopand-stay signal and a diverging route stop-andstay signal located at the end of the stretch of single track and governing the movement of traflie into the main track and siding respectively, a switch machine for operating the switch of said siding, means for controlling said switch machine and signals from a distant tower, the control for said signals depending upon the operated position of said switch machine, means for locking said switch machine against operation comprising, a stick relay having a stick circuit which is closed if a signal at least braking distance away from said switch governing traffic toward said switch is either in the caution or stop condition or the first track circuit beyond said signal is not occupied, and means for rendering said locking means inefiective and rendered active if an operator at such tower and a trainman at such switch simultaneously operate suitable manually operable means.

11. Means for controlling a switch at a siding a considerable distance from a control point comprising, a switch machine, a plurality of signals adjacent said switch for governing the movement of traffic by said switch, approach locking means for locking said switch machine against operation under predetermined traffic conditions, and means for rendering said approach locking means ineffective requiring two manually operable devices to be operated simultaneously and all of said signals to be at stop, one of said manually operable devices being located at such switch and the other of said manually operable devices being located at said control point.

12. In a central control train dispatching system, the combination with an outlying track switch, a switch machine for operating said track switch, signals governing the movement of trains by said track switch, and unitary supervisory control means for controlling both said signals and said switch machine, said supervisory control means being so constructed and interconnected with said switch machine and said signals that the approach of a train under proceed indications of said signals will prevent change of said control means to cause operation of said switch machine, and means for informing the engineer as to the progress of such train along the track.

13. An outlying switch and signal control mechanism for railway systems comprising, a track having an outlying passing siding distant to a tower, a track switch for said siding, a power operated switch machine for operating said track switch, a siding signal for governing the movement of traflic into said siding, a main signal for governing the movement of trafiic into the main track adjacent said siding, electro-responsive means controlled by a lever in said tower for controiling said switch machine and signals, a circuit for causing said main signal to indicate proceed closed when favorable trafiic conditions exist ahead, said switch machine assumes the main track position and said control means assumes a certain energized condition, another circuit for causing said siding signal to indicate proceed closed when said switch machine assumes the siding position and said control means assumes another energized condition, an approach locking circuit closed when there is no train approaching which if open prevents operation of said switch machine, other means for preventing the operation of said switch machine if any of said signals indicate proceed, and means requiring the cooperation of two persons for permitting operation of said switch machine when said approach locking circuit is open.

14. An outlying switch and signal control mechanism for railway systems comprising; a

track having an outlying passing siding distant to a tower; a track switch for said siding; a power operated switch machine for operating said track switch; means for controlling said switch machine from a distant point; an proach zone having a signal governing traffic toward said switch; a relay which assumes its de-energized position when a train enters said zone from one end, if said signal then indicates proceed and remains de-energized so long as said zone is occupied by such train irrespective of the indication of said signal, said relay remaining in its energized position if a train enters said zone from the other end; and means for preventing the operation of said switch machine controlling means if said relay is de-energized.

15. An outlying switch and signal control mechanism for railway systems comprising, a track having an outlying passing siding distant to a tower, a track switch for said siding, a power operated switch machine for operating said track switch, means for controlling said switch machine from said distant tower, two approach zones, one extending in one direction and the other extending in the other direction from said track switch, and means for preventing operation of said controlling means for said switch machine when there is an approaching train in either of said approach zones but not preventing operation of said switch machine when there is a departing train in either of said approach zones.

16. An outlying switch and signal control mechanism for railway systems comprising; a track having an outlying passing siding distant to a tower; a track switch for said siding; a power operated switch machine for operating said track switch; means for controlling said switch machine from said tower; an approach zone having a signal near the end distant to said track switch; and approach locking means adjacent the trackway controlled by said signal and effective to prevent operation of said switch machine controlling means when a train which entered said approach zone from the end distant to said track switch is occupying such zone if said signal indicated proceed when the train accepted it, but which is ineffective to prevent such operation of the switch machine if the train in question accepted said signal when indicating adverse traflic conditions or if said control zone is occupied by a train moving in the opposite direction.

1'7. An outlying switch control mechanism for railway systems comprising; a track having an outlying passing siding distant to a tower; a track switch for said siding; a power operated switch machine for operating said track switch; means for controlling said switch machine from said tower; a track circuited fouling section for said track switch; an approach section extending from said fouling section to the next signal location; a signal at said signal location governing the movement of traffic toward said track switch; and switch machine control locking means including a stick relay responsive to the indications of said signal when approached by a train and effective to prevent operation of said switch machine if said fouling section is occupied or if said approach section is occupied by an approaching train which accepted said signal at proceed, but which is ineffective if said approach section is occupied by a departing train or is occupied by an approaching train which accepted said signal at stop.

18. In a system for controlling a distant track switch, the combination with a railway track diverging through the medium of a track switch into two tracks, a fouling track circuit associated with said track switch, a switch machine for operating said track switch, a home signal adjacent said track switch for governing the passage of trains toward the points of said track switch, a distant signal located at the next signal location in the rear of said home signal, unitary control means for controlling said switch machine from a distant point and'for permit ting said home signal to assume a condition in accordance with traffic conditions, and means for preventing operation of said switch machine by said control means if there is a train approaching which accepted said distant signal at proceed or there is a train occupying said fouling track circuit, said means including a stick relay adjacent the trackway having pick up and stick circuits both controlled in accordance with the indications of said distant signal.

19. In a system for controlling a distant track switch, the combination with a railway track diverging through the medium of a track switch into two tracks, a fouling track circuit associated with said track switch, a switch machine for operating said track switch, a home signal adjacent said track switch for governing the passage of trains toward the points of said track switch, governed in accordance with traffic in advance of such train, a distant signal located in the rear of said home signal governed in accordance with traffic between said home and distant signal, unitary control means for controlling said switch machine and signals from a distant point, and approach locking means for preventing operation of said control means if there is a train approaching which accepted said distant signal at proceed'but which will not prevent such operation if there is a train approaching which accepted said distant signal at cau- .tion, and manually operable means for releasing the locking of said approach locking means.

20. In a non-train-order train dispatching system, the combination with an outlying siding, a track switch for said siding, a switch machine for operating said track switch, signals governing the movement of trains by said track switch, and unitary supervisory control means for controlling both said signals and said switch machine, said supervisory control means being so interconnected with said switch machine and said signals that the approach of a train within a certain limited zone if said train enters said zone under clear trafiic conditions ahead will prevent operation of said control means but will not' prevent operation thereof if said train entered said zone when adverse traflic conditions in advance were indicated.

21. Semi-automatic switch control apparatus comprising, a track switch connecting a railway track section to either a main track or a diverging track, a switch machine for operating said track switch, electrically operated control means for controlling said switch machine, a lever at a distant point for controlling said electrically operated control means, an app-roach zone, a signal near the entrance to said approach zone governing the movement of trains into said zone, and means adjacent the trackway and responsive to the presence of a train in said approach zone and the indications of said signal for preventing when there is a trainin said zone approaching said switch whichaccepted said signalwhile indicating proceed but not preventing operation of said switch machine if said train accepted a restrictive indication from said signal.

22. In an approach locking system, the combination with an approach zone divided into two sections, a track switch at one end of said approach zone, a switch machine for operating said track switch, a distant signal at the junction between said sections governing the movement of trains toward said switch machine, a home relay governed in accordance with traflic conditions ahead of said signal for governing said signal, a track relay indicating traflic conditions of the section in the rear of said signal, an approach relay of the stick type, a pick-upcircuit for said approach relay closed if said home relay and said track relay are energized, a stick circuit for said approach relay including a front contact of said approach relay in series with a front contact of said track relay connected in multiple with a contact closed when said signal indicates caution or stop, and means for permitting operation of said switch machine only if said approach relay is assuming its energized condition.

23. In an approach locking system, the combination with an approach zone divided into two sections, a track switch at one end of said ap: proach zone, a switch machine for operating said track switch, a distant signal at the junction between said sections governing the movement of trains toward said switch machine, a normally energized approach relay adjacent the trackway and controlled by said signal, means for effecting de-energization of said approach relay if a train moving toward. saidswitch machine enters said zone when said signal is indicating proceed but not effecting de-energization of said approach relay if said signal is then indicating adverse traflic conditions, and means for permitting operation of said switch machine only if said approach re lay is energized.

24. In an approach locking system, the combination with an approach zone divided intotwo sections, a track switch at one end of said approach zone, a switch machine for operating said track switch, a distant signal at the junction between said sections governing themovement of trains toward said switch machine, a home relay governed in accordance with traffic conditions ahead of said signal for governing said signal, a track relay indicating traffic conditions of the section in the rear of said signal, an approach relay of the stick type, a pick-up circuit for said approach relay closed only if said home relay and said track relay are energized, a stick circuit for said approach relay including a front contact of said approach relay inseries with a front contact of said track'relay connected in multiple with a contact closed when said signal indicates caution or stop, other signals adjacent said track switch for governing the movement of trains over said track switch, and means for permitting operation of said switch machine only if said approach relay is energized and said other signals are all at stop.

25. In an approach locking system, the combination with an approach zone divided into two sections, a track switch at one end of said approach zone, a switch machine for operating said track switch, a distant signal at the junction be tween said sections governing the movement of trains toward said switch machine, a normally energized approach relay adjacent the trackway and governedin accordance with the indications of said signal, means for eifecting de-energization of said approach relay if a train moving toward said switch machine'enters said zone when said signal is indicating proceed but not'efiecting de-energization of said approach relay if said signal is then indicating adverse traffic conditions, other signals adjacent said track switch for governing the movement-of trains over said'track switch, and means for permitting operation of said switch machine only if said approach relay is energized and said other signals are all at stop.

26. Apparatus for safely operating a distant track switch comprising, a power operated switch machine for operating 'such track switch, a control relay controlled from a local point for con-. trolling said switch machine, an approach zone, a signal visible when a train enters said approach zone, and approach locking means adjacent the trackway for preventing a change of said control relay effecting operation of said switch machine, said means depending for its operation upon the occupancy of said approach zone and on the indicating condition of said signal when said zone becomes occupied.

27. Apparatus for safely operating a distant track switch comprising, a power operated switch machine for operating such track switch, a control relay controlled from a local point for controlling said switch machine, an approach zone, a signal visible when a train enters said approach zone, and approach locking means for preventing an energization of said control relay effecting operation of said switch machine, said means depending for its operation upon the occupancy of said approach zone andon the indicating condition of said signal when said zone becomes occupied by a train moving ina particular direction.

28. In a train dispatching system, means for controlling a railway switch and a signal governing train movements over said switch from a remote office, approach locking means rendered effective if a train enters an approach zone when the signal which said train is approaching indicates proceed but not if a train enters such zone while said signal indicates stop, means for preventing operation of said switch while a train occupies the track section containing said switch, control means for operating said switch and signals from a remote ofiice, means controlled by said approach locking means when a train is in said approach zone for preventing the operation of said control means to effect a change in route, but not to prevent the operation of said control means to put to stop the signal of the existing route.

29. In a train dispatching system, means for controlling a railway switch and a signal governing train movements over said switch from a remote oflice, approach locking means rendered effective if a train enters an approach zone when the signal which said train is approaching indicates proceed but not if a train enters such zone while said signal indicates stop, relay control means at the switch for operating said switch and signals from a remote ofllce, means controlled by said approach locking means when a train is in said approach zone for preventing the operation of said control means to effect a change in the position of said'switch, but not to prevent the operation of said control means to put said first'signal to stop.

30. In combination, a distant track switch, a switch machine for-operating said track switch, a control'relay for controlling said switch machine,

a lever at a local oflice for controlling said control relay, a signal associated with said switch, and a stick relay which if deenergized prevents the control of said control relay and which stick relay is controlled by said signal and by traffic conditions in an approach zone to said track switch, said stick relay including a holding circuit containing its own front contact, whereby if said stick circuit is momentarily broken said stick relay will thereafter remain deenergized until picked up by a pick-up circuit.

31. In combination, a distant track switch, a switch machine for operating said track switch, a control relay for controlling said switch machine, a lever at a local oiiice for controlling said control relay, a signal associated with said switch, a stick relay which if deenergized prevents. the control of said switch machine and which stick relay is controlled by said signal and by tramc conditions in an approach zone to said track switch, and means manually operable only by a person at said track switch location for permit ting control of said switch machine from said local oifice when said stick relay is deenergized.

32. In combination, a distant track switch, a switch machine for operating said track switch, a control relay for controlling said switch machine, a lever at a local office for controlling said control relay, a stick relay provided with a stick circuit including its own front contact, which stick relay if deenergized prevents the control of said switch machine from said local oflice and which stick relay is controlled by trafiic conditions in an approach zone to said track switch, and means manually movable only by a person at the switch for permitting power operation of said switch machine in spite of the deenergization of said stick relay.

33. In combination, a distant track switch, a switch machine for operating said track switch, a control relay controllable from a local office for controlling said switch machine, locking means for under certain trafiic conditions preventing the control of said control relay from said local ofiice, and two independently manually controllable devices for rendering said locking means ineiiective one of which is controlled at said local oflice and the other of which is controlled from a point adjacent said track'swiitch.

34. In combination, a distant track switch, a switch machine for operating said track switch, a control relay for controlling said switch machine, a lever at a local ofiice for controlling said control relay, a stick relay which if deenergized prevents the control of said switch machine from said local ofiice and which stick relay is controlled by traiiic conditions in an approach zone to said track switch, and means requiring cooperation of a person at said local oflice with a person at said track switch to afford control of said switch machine while said stick relay is deenergized.

35. 'In combination'a track switch located at a. distant point, a switch machine for operating said track switch, a lever, a stick relay for when deenergized preventing control of said switch machine from a local oil'ice, means controlled by a preliminary movement only of said lever for closing a pick-up circuit for said stick relay and controlled by a second movement of said lever to close an operating circuit for said switch machine, and a stick circuit for said stick relay for holding said stick relay energized while said lever assumes a position to close said operating circuit.

36. In combination a track switch located at a distant point, a switch machine for operating said track switch, an approach section for said track switch, a lever, a stick relay for when deenergized preventing control of said switch machine from a local ofiice, means controlled by a preliminary movement only of said lever for closing a pick-up circuit for said stick relay providing said approach section'is not then occupied and controlled by a second movement of said lever to close an operating circuit for said switch machine, and a stick circuit for said stick relay for holding said stick relay energized while said lever assumes a position to close said operating circuit.

3'7. In combination, a distant track switch, a signal for governing traific over said track switch, a switch machine for operating said track switch, means for controlling said switch machine from a local ofiice, locking means governed jointly by traflic conditions in an approach section for said track switch and the indicating condition of said signal for at times preventing control of said switch machine from said local oifice, and other means located at the switch for rendering said locking means ineffective.

38. In a railway traflic controlling system, a track switch, a switch machine for controlling said track switch, a signal governing the movement of trailic over said track switch, an approach zone, lock means for preventing control of said switch machine dependent on both the condition of said signal when a train entered said approach zone and on the condition of said signal when said switch machine is attempted to be operated, and other means local to said track switch and manually operable for rendering said lock means ineffective providing said signal is then at stop.

39. In combination, a stretch of railway track including an approach track section and a detector track section, a switch leading from the detector track section, a signal to govern the movement of trafic from the approach track section into the detector track section, a track relay for each said track section, an indicating relay energized when the signal is at stop position, a route locking relay to control the operation of the switch arranged to permit operation of said switch when energized and to prevent operation of the switch when de-energized, and a circuit to energize said route locking relay including a front contact of the indicating relay and a. front contact of each said track relay.

40. In a railway traffic controlling system, a track switch, a switch machine for actuating said track switch, a signal governing the movement of trafiic over said switch, means for controlling said switch machine and said signal. concurrently from a distant control point, an approach zone, and two means for separately preventing control and operation of said switch machine, one of said means being dependent upon the indicating condition of said signal at the time a train enters said approach zone, and the other of said means being dependent upon the indicating condition of said signal at any time when said switch machine is attempted to be operated.

SEDGWICK N. WIGHT. 

